A container blank and, above all, a container of the type stated by way of introduction are known from, for instance, WO 99/41155 which discloses a container of a collapsible type, comprising three wall portions, two of which form opposing side walls and a third forms a bottom wall. The walls consisting of a flexible plastic material are bendable and joined to each other to define a compartment the volume of which depends on the relative position of the walls. In its unfilled state, the container, and thus its container blank, is flat.
The simplest type of container blank has a rectilinear geometry. If a carrying means is to be arranged in such a rectilinear container blank, this occurs by a handle-forming corner or lateral portion of the container blank being defined by a connecting portion. This means that the compartment in a container made of the container blank will have an asymmetric geometry instead of a symmetric and thus well-balanced geometry. A filled container having such an asymmetric compartment has a certain tendency to tilt forwards in use since the centre of gravity is moved to a position in front of the centre axis of the container blank. The tendency towards tilting also means that the flexible container, which because of its collapsible construction has no rigidity, in some cases may tend to collapse, at its front edge, like a filled bag that is placed on its end. This is to be seen as wrinkling along the connecting portion especially at the front edge of the container. Such wrinkling may affect the appearance of the container. Moreover, in long-term careless handling of the container, for instance during bumpy transport, damage due to wear may sometimes arise on the container material.
The problems associated with the movement of the centre of gravity and the subsequent wrinkling will be complicated if the container blank, and the container made thereof, has an outer curvature, such as the one shown in the above-mentioned WO 99/41155. In fact curvatures, in particular if they are sharp, increase the tendency towards wrinkling. Moreover such curvatures imply that the amount of material waste arising in the manufacture of the container blank increases.